Aging apparatus for transistors



Oct. 29, 1957 w. D. BOYNTON ETAL 2,810,951

AGING APPARATUS FOR TRANSISTORS 2 Sheets-Sheet 1 Filed May 27, 1954llW/[NTORS I W D. BOY/VTO/V R L.MULLER ATTORNEY United States Patent2,810,951 AGING APPARATUS FOR TRANSISTORS Wentworth D. Boynton,Wyomissing, and Paul L. Mueller, Temple, Pa., assignors to WesternElectric Company, Incorporated, New York, N. Y., a corporation of NewYork Application May 27, 1954, Serial No. 432,775 4 Claims. (Cl.29--25.3)

This invention relates to aging apparatus for transistors.

In the manufacture of transistors, as is common practice with vacuumtubes and other electrical components, it is necessary that they beelectrically aged by applying specific voltages, depending on the codeof the transistor, to the electrodes thereof for a pre-determined periodof time.

It is, therefore, the principal object of the invention to provide anaging cabinet in which transistors of a variety of codes or types may beconveniently aged.

in accordance with the above object, the cabinet is provided with meansfor adjusting the voltages applied to the transistors, receptacles forreceiving any of a series of transistor aging trays each wired for andloaded with transistors of a particular type or code and designed forspaced-stacking, a fan for circulating air around the trays and a timerto cut off the power after a selected aging period.

According to an important feature of the invention the inadvertentapplication of excessive potential to the transistors is prevented by anelectrical interlock which requires the operator to return the voltageadjusting means to low voltage position before the aging circuits can beenergized.

Another important feature of the apparatus is that power isautomatically cut off and an indicator is operated if the cabinet doorsare opened thereby assuring that no trays have been added or removedduring the aging cycle.

According to another feature of the invention, in order to facilitaterepairing the trays, in case of any trouble developing therein, thetransistor sockets are mounted in sub-assemblies each with its properresistors. The sub-assemblies may be removed as a unit and may beconveniently repaired or replaced.

These and other features of the invention will be more fully understoodfrom the following description taken in conjunction with theaccompanying drawing, in which:

Fig. 1 is a front view of the cabinet with one of the doors open showingseveral trays stacked therein;

Fig. 2 is a side view of the cabinet of Fig. 1 showing a fan andadjustable shutters for controlling the circulation of the air over eachtray in the cabinet;

Fig. 3 is a plan view of one of the trays;

Fig. 4 is a plan view of one of the sub-assemblies for a tray;

Fig. 5 is a view of the tray of Fig. 3 along the plane of line 5-5;

Fig. 6 is a schematic diagram of a sub-assembly, and

Fig. 7 is a schematic diagram of the electrical circuit by which theapparatus is controlled.

As illustrated in the drawing, the cabinet in general comprises a steelframe structure having a control panel 8 on which the meters, rheostatsor variable autotransformers, indicators and circuit breaker aremounted, a sheet metal divided, tray receiving portion 9 having openmeshed doors 43, a housing for a ventilating fan 10 and a power supplyhousing portion 11- As seen in Fig. 2 baffle elements are disposed atthe back of each tray compartment 12 and are individually mounted to thecabinet to control the amount of air passing through each compartment,the angular setting of each baffle being determined experimentally togive equal circulation of air around each tray. The air is taken inthrough the open mesh doors 43, passes through the tray compartments 12into a chamber 76 in the back of the cabinet and is exhausted throughthe aperture in the rear of the cabinet for the fan.

Trays 14 contain a plurality of sub-assemblies 15 mounted by bolts 18 toa top plate 17 having a plurality of apertures for the transistorsockets 70. Each of the subassemblies 15 is provided with 6 sockets 70having 3 contact elements 19, 20 and 21 for receiving transistors havingemitter, collector, and base electrodes respectively. The emitter andcollector contacting elements 19 and 26 are connected throughappropriate biasing resistors 22 and 23 to conductors 24 and 25respectively which in turn are attached to tray bus bars 26 and 27mounted by insulating bracket 28 along one side of the top .plate 17.The bias resistors 22 and 23 are chosen for the particular adjustedvoltage of the tray bus bars and the code of transistors to be aged.Thus the trays may be wired for transistors of different codes, anidentification plate 42 being provided on the front of the tray fornoting the code for which the tray is Wired.

Lamps 29 and 39 on the front panel 31 of the tray are connected betweenground potential and the bus bars through Wires 32, 33 and 34 forindicating the application of power to bus bars 26 and 27. The tray busbars 26 and 27 are connected to the cabinet power source and the trayframe is connected to ground potential through plug 35 mounted at theback end of the tray which engages any one of a plurality ofcorresponding sockets in the cabinet. The electrical circuit forenergizing these sockets will be discussed below.

By providing stand-ofis 37 mounted on each corner of the top plate 17 ofeach tray and corresponding receiving wells 40 in each corner of thebottom plates 37, it is possible to stack loaded trays awaitingelectrical aging in any convenient place outside of the cabinet withoutrequiring a compartmented holder.

The control circuit shown in Fig. 7 is used for supplying theappropriate tray bus bar voltages to sockets 36 from a volt, 60 cycleper second source 48. This circuit includes a timer 59 for opening thepower supply circuit at the end of a pre-set aging period and alsoincludes means for preventing the application of excessive initialvoltages, indicates power failure and removal or addition of traysduring the aging period which would require the opening of the cabinetdoors.

Specifically, the sockets 36 are energized from emitter and collectorsupply rectifiers 44 and 45 which in turn are energized by rheostats orvariable autotransformers 46 and 47 respectively. The inputs to theautotransformers are connected in parallel and the application of powerthereto is controlled by relay 51 which must be operated to connect thesource 48 thereto through power distribution lines 63 and 64. A timemeter 52 and an indicator 53 are bridged across the inputs to theautotransformers. The time meter 52 records the aging time while theindicator 53 conveniently shows that the aging circuit is energized.Before control relay 51 can be energized to close the aging circuit,autotransformer switches 54 and 55, door switches 56 and 57 and switch58 controlled by timer 59 must be closed. Switches 54 and 55 are onautotransformers 46 and 47 respectively and are closed only when theautotransformers are set for minimum or a reduced output voltage. Thisis one type of simple electrical interlock which requires the operatorto return the autotransformers to minimum out put settings to preventthe inadvertent application of high initial voltages to the transistorsin the trays. Once the relay 51 is operated the autotransformers may beadjusted as required since, by operation of the relay 51, switches 54and 55 are by-passed from the relay energizing circuit by lead 60,operated contact 61 of relay 51 which is jumpered to contact 62connected to the distribution line 63.

a Door switches 56 and 57 are closed when the doors are closed andopening either door for'the removal or addition of trays during theaging cycle will open the control relay circuit and thereby open theaging circuit. Before the aging circuit can be closed again theautotransfor'mers must be returned to minimum output set tings and thedoors must be closed. The timer 59, of course, must be adjusted to theprescribed setting in order to close its contact 58. The fan motor 65 isconnected in parallel with the relay 51 winding so that air will becirculated through the cabinet whenever the relay is energized.

Distribution lines 63 and 64 of the aging control circuit are connectedto the source 48 through a circuit breaker 66, mounted for convenienceon the control panel 8. An indicator lamp 68 bridged across lines 63 and64 is energized when the lines 63 and 64 are connected to the source.Once the aging cycle has been started if the cycle is interrupted bypower failure or by one of the cabinet doors being opened, an indicator69, which is connected to line 64 through timer switch 58 and to line 63through the released contact 61 of the relay 51, is energized.

As seen in Figs. 1 and 7 voltmeter 71 and 72, connected across theoutput of the emitter and collector supply rectifiers 44 and 45, areprovided for indicating the adjusted outputs of the .emitter andcollector -supplies respectively. In addition, a multi-range ammeter 73is provided in the output of the collector supply rectifier.

It is to be understood that the above described arrangements. are simplyillustrative of the application of the principles of the invention.Numerous other arrangements may be readily devised by those skilled inthe art which will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

1. Transistor aging apparatus comprising a cabinet, means forcirculating air through the cabinet, adjustable sources of transistorelectrode voltages for the cabinet, a

1 plurality of trays for the cabinet, said trays having transis- -torreceiving sockets and circuits therefor including electrode biasimpedances, means for connecting said circuits to the sources in thecabinet, means for spaced-stacking i the trays in the cabinetto permitengagement of the connecting means, means including an adjustable timerfor de-energizing the sources after a selected aging period, switchingmeans controlled by the power sources to permit energizing the sourcesonly when the sources are set for reduced output and means forby-passing the switching means when the sourcesare energized.

2. Apparatus according to claim 1 in which the sockets are mounted onthe trays in removable sub-assemblies, each socket'having its respectivebias impedances wired thereto and the connecting means include bus barsin the trays to which the sub-assembly wiring is connected. a V

3. Transistor aging apparatus comprising a plurality of trays havingtransistor receiving sockets and wiring for a particular code oftransistors, a cabinet having a tray receiving portion, means forcirculating air through the cabinet, sources of transistor electrodevoltages for the cabinet, a rheostat in each of the sources for varyingits output voltage, means for connecting the tray wiring to the sourcesin the cabinet, means for spaced-stacking the trays in the cabinet topermit engagement of the connecting means, means including an adjustabletimer for de-energizing the sources after a selected aging period,switching means controlled by the rheostats to permit energizing thesources only when the rheostats are set for lower-than normal outputsfor the sources, and means for by-passing the switching means when thesources are energized. V

4. Transistor aging apparatus comprising a cabinet, means forcirculating air through the cabinet, sources of transistor electrodevoltages for the cabinet, a variable autotransformer in each of thesources for varying its out put voltage, an energizing source of powerfor the electrode sources, a relay for connecting the energizing sourceto the electrode sources, an energizing circuit for the relay includingswitches controlled by the autotransforrners to permit operation of therelay to connect the energizing source to the electrode sources onlywhen the autotransforrners are set for lower than normal output for thesources, means for try-passing the switches when the electrode sourcesare energized, a plurality of trays having transistor receiving socketsand wiring for a particular code of transistors, means for connectingthe tray wiring to the sources in the cabinet, means for spacedstackingthe trays in the cabinet to permit engagement of the connecting means,means including an adjustable timer and contacts controlled therebyconnected in the relay energizing circuit for opening said circuit aftera selected aging period.

No references cited.

